World on course for warmest year
- 4 December 2014
- From the section Science & Environment
This year is in the running to be the hottest globally and for the UK since records began, early estimates show.
In the first 10 months of 2014, global average air temperature was about 0.57 Celsius above the long-term average.
And the first eleven months in the UK have produced an average temperature 1.6C above the long-term.
A separate study by the UK Met Office says the observed temperatures would be highly unlikely without the influence of greenhouse gases produced by humans.
The global figures come in estimates from the UN's World Meteorological Organisation (WMO).
If this year's current global trend continues for the next two months, the previous record years of 1998, 2005 and 2010 will be overtaken by a narrow margin.
The Secretary-General of the WMO, Michel Jarraud, said the preliminary data for 2014 was "consistent with what we expect from a changing climate."
1878: Strong El Nino×
In 1878, there was a strong El Nino (where warmer water rises to the surface of the Eastern Pacific Ocean) and this is seen very clearly as a large spike in global temperature. This event was remarkable for an extreme drought in India where it is an estimated more than five million people died. There were droughts in nothern China also associated with this El Nino. The famine caused by the drought in India spurred scientists to begin work on climate patterns, leading eventually to discovery of the El Nino-related “Southern Oscillation” - the idea that the ocean and atmosphere are connected.
1940s: Weaker El Nino×
The warm early 1940s were affected by a weaker, but protracted, El Nino.
1991: Mt Pinatubo eruption×
In June 1991 Mt Pinatubo in the Philippines erupted, releasing millions of tons of sulphur dioxide into the atmosphere. This resulted in a decrease in the temperature worldwide.
1998: Record-breaking year×
For a long time. the strong El Nino around 1997/98 meant that 1998 topped the rankings for the world’s warmest year. This has since been overtaken.
1960/70s: Cooler years×
The cool 1960s and 1970s are likely to have resulted at least partly from man-made air pollution from sulphate particles. Steps taken towards cleaner air resulted in warming.
In comments released with the new figures, he said:
"The provisional information for 2014 means that 14 of the 15 warmest years on record have all occurred in the 21st century."
In unusually strong language, Mr Jarraud highlighted the impacts of the weather extremes.
"Record-breaking heat combined with torrential rainfall and floods destroyed livelihoods and ruined lives. What is particularly unusual and alarming this year are the high temperatures of vast areas of the ocean surface, including in the northern hemisphere."
And he asserted that the new figures confirm the key trend in climate change: "There is no standstill in global warming."
This is a reference to the hotly-debated "pause" in global warming which has seen no major increases in temperature since 1998.
A year of extremes
The WMO report highlights a number of record-breaking weather events around the world:
- The UK's last winter in which 12 major Atlantic storms battered the country bringing nearly double the usual rainfall.
- In September, parts of the Balkans received more than double the average monthly rainfall and parts of Turkey were hit by four times the average.
- The town of Guelmin in Morocco was swamped by more than a year's rain in just four days.
- Western Japan saw the heaviest August rain since records began.
- Parts of the western US endured persistent drought (as we reported from Oklahoma last June, as did parts of China and Central and South America).
- Tropical storms, on the other hand, totalled 72 which is less than the average of 89 judged by 1981-2010 figures. The North Atlantic, western North Pacific and northern Indian Ocean were among regions seeing slightly below-average cyclone activity.
The provisional record for 2014 is only slightly higher than for the previous record year of 2010 - one-hundredth of a degree - which was 0.56C above the long-term average.
However climate scientists point out that all but one of the warmest 15 years have come in this century.
This suggests that although there have been no big jumps in temperature in the past 16 years, the period as a whole is proving to be exceptionally warm.
The waters of the eastern Pacific are among those to have warmed significantly - a situation which might normally be expected to trigger so-called El Nino conditions that often boost global warmth. However, puzzlingly for scientists, these have yet to materialize.
So if 2014 does prove to set a new record for global average temperatures, it will have been without the warming contribution of an El Nino.
For the UK, temperatures so far this year suggest the country is on course for a new record - judged by data stretching back to 1910.
And there may also be a new high in the longer-running Central England Temperature record - which started in 1659.
Although no single month in 2014 has set a new record, every month except August has seen above-average temperatures so the whole year so far has been consistently warm.
Meanwhile, the Met Office has studied the extent to which manmade greenhouse gases are behind the warming.
A paper issued to coincide with the WMO figures says that although "one warm year does not necessarily say anything about long-term climate change" new research shows how human influence made record temperatures more likely.
Met Office scientists ran computer models of two versions of the climate - one with data drawn from real conditions and the other with simulations of the atmosphere in which the greenhouse gases had been removed.
The results were used to calculate a measure known as a "Frequency of Attributable Risk" (FAR) to describe the likelihood of a human influence in warming.
For the UK, the models show that this year's potential record temperature was made ten times more likely because of the presence of carbon emissions in the atmosphere.
Adam Scaife, a Met Office scientist involved in the research, told the BBC about the results on a global scale:
"It turns out to be very unlikely to have the temperatures we've seen this year in the world where we've artificially removed the anthropogenic carbon dioxide.
"In the world that would have been, it's very unlikely that we'd see the temps we're seeing now."
The WMO's report on the state of the global climate is published every year to coincide with the UN's annual negotiations on climate change, this time under way in Lima in Peru.
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